Abstract
Farmland, for the purposes of this book, refers entirely to tillage or tillage and livestock (mixed) systems in the lowlands, largely below an altitude of 300 m. Upland pastures and reseeded leys, dominated by livestock rather than tillage are considered in Chapter 11. Farmland which is devoted to cereals, other crops and horticulture accounts for 19.6% of the total land surface of Britain, with cereals alone accounting for 14.9%. This area is sixteen times the combined area given over to all Nature Reserves with statutory protection in the UK (Potts, 1991). For the context of management farmland comprises both cropped land and non-cropped land. The non-cropped habitats are generally remnants of those types discussed in other chapters but their management on the farm is fundamental to improving a farm for wildlife. Furthermore, their management is best considered as an integral part of the farmland landscape in a pragmatic and practical manner if the land manager or farmer is to undertake the work within the farm economy.
The ability to drain and till large areas of land with reduced labour, and the parallel increase in chemical fertilisers and pesticide treatments, followed by crop specialisation and associated monoculture, has led to the greatest detrimental impact on wildlife diversity (Table 9.1). Such 'intensification' is defined as the exclusion of non-crop organisms (pests and competitors) leading to the maximum use of land for food production. Intensification has resulted in fragmentation and direct habitat loss such as hedgerow removal, pond infilling, woodland fragmentation, drainage of wet meadows and saltmarsh. Loss of edges, known to be good for wildlife in most circumstances, has been the result of monoculture farming rather than mixed diverse farming. Intensification practices have involved the abandonment of rotations and undersowing, conversion of permanent pasture to temporary leys, use of inorganic fertilisers, a switch from spring sown to autumn sown crops, earlier hay making and increased cutting of grass for silage early in the summer, and the development of new strains of cereals which grow at higher densities under artificial fertilisation, thus shading out conservationally interesting arable weeds. Finally, wildlife impacts have been most noticeably seen as a result of the directly toxic effects of various pesticides. Whilst the worst of these are now banned, many of the new generation pesticides can have indirect effects on wildlife by operating through the food supply. Table 9.1 gives an analysis of changes to farming practice during this intensification period, the respective ecological impacts and the major wildlife responses. Much of farmland management for conservation therefore involves reversing these impacts in a way which has least effect on the farms' main activity - the production of food, thereby integrating good conservation practice and good farming practice.